The Explorers' Club, № DCCCLXV

The Space Race
The North American X-15, a rocket-powered hypersonic aircraft operated jointly by N.A.S.A. & the U.S. Air Force: Three X-15s flew one hundred ninety-nine flights from 1959-1968, carried aloft by two Boeing NB-52 motherships; X-15 records include the greatest speed by a crewed, powered aircraft, Mach 6.7 (4,520 M.P.H.), & an altitude of sixty-seven miles, above the Kármán line—into outer space.

Commentary: The Space Shuttle Orbiter flew faster during atmospheric re-entry than the X-15 (Mach 25 > Mach 6.7), but by that point in its flight, the Space Shuttle was an unpowered glider.

One X-15 was destroyed in a fatal crash; the two surviving aircraft are on display at the National Air & Space Museum in Washington, D.C. & the National Museum of the United States Air Force in Dayton, Ohio.

Semper exploro.